1. Field of the Invention
The present invention relates to an image pickup apparatus.
2. Description of the Related Art
An image pickup apparatus in which, an image pickup element having pixels for detecting focal point (hereinafter, ‘focal-point detection pixels’) and pixels for picking up image (hereinafter, ‘image-pickup pixels’) mixed in a pixel row in a predetermined direction is used, has been proposed (Specification of Japanese Patent No. 3592147).
In such image pickup apparatus, it is common to have a photoelectric conversion portion which converts an optical image formed by an image pickup optical system to an electric signal.
When excessive light is incident on the photoelectric conversion portion, there is an overflow, in which an excessive electric charge flows from a pixel to an adjacent pixel. Due to the overflow, a blooming phenomenon which becomes a false signal occurs. As a typical example of a function to prevent the blooming phenomenon, a structure in which, an overflow drain is to be provided has hitherto been known.